The paper presents the seismic stability analysis of geosynthetic reinforced unsaturated soil slopes. The limit equilibrium approach was used to conduct the analysis, which took into account the logarithmic spiral failure surface. The analysis is carried out for two types of backfill materials, namely high-quality backfill (HQB) and marginal quality backfill (MQB). They are classified based on the amount of fines content in the filling material. The analysis also considers the surcharge load applied to the backfill. The influence of horizontal seismic accelerations (kh), backfill soil friction angle ( \(\phi\) ), surcharge load (q), pore size exponent (n), the inverse of air entry value (α), rainfall intensity (qus), and coefficient of permeability of saturated soil (ks) on the reinforcement force coefficient (K) needed to stabilize the reinforced soil slopes is presented. The effect of suction on the reinforcement force coefficient (K) is also clearly demonstrated in the present study.